Decking markets in Canada lack options of hybrid designs and are generally limited to smooth 5/4” or 2x6” of either pressure treated wood, cedar, tropical hardwoods or wood plastic composites. Profiled decking has been unsuccessful in entering the Canadian market on a large scale even though globally it is more prevalent. This report looks to leverage FPInnovations’ expertise to identify opportunities to improve the stability, durability, performance and competitiveness of wood decking by combining profiling and treatment with additional non-wood materials. This information will be used to develop prototypes of novel wood-based decking products that would suit the needs of Canadian consumers as well as maintaining or expanding the solid wood decking market for Canadian producers. Six hybrid decking models were conceptualized to address market concerns about wood decking.
In this project, the main objective was to evaluate the “best bet” experimental mat structure design previously identified by FPInnovations in 2018/19. This mat structure was comprised of three strand size classes incorporated into six equal weight mat layers. Both experimental and control panels were prepared at 39lb/ft³ and 35lb/ft³ densities and tested for dry static bending, single cycle bending (D4), concentrated static load, thickness swell, and internal bond strength.
The findings of recent studies from both eastern and western Canada have shown that the drying behaviour of subalpine fir (A. lasiocarpa) and balsam fir (A. balsamea) is similar, which allows common solutions to be applied based on research conducted on one species of fir or the other. This article summarizes previous research findings and good practices that can be adopted in the short term to improve the drying of fir.
Continuous drying is still in its relatively early stages and mills are currently dealing with process adjustments to obtain desired throughput and quality of the final product. Field measurement carried out in 2015-16 illustrated a number of opportunities for process optimization involving each of the three main stages of current continuous kilns. Simulations of industrial continuous drying at laboratory level performed in 2016-17 were successful and allowed the evaluation of each of the drying stages to be fully characterized (lumber temperatures, drying schedule conditions of dry and wet bulb temperatures). Thus, different drying schedules provided an excellent opportunity to examine the impact of schedule conditions on drying defects, drying rates and kiln residence times.
The main objectives of the project for 2017-18 were to simulate continuous drying in laboratory conditions for different products, products mix, species and green sort groups. In addition, a detailed evaluation of potential technologies was carried out to explore the concept of dynamically adjusting speed (push rates), based on drying rates and moisture content.
Piecewise regression was used to identify the optimum push rate and suggest design modifications of continuous kilns. This method proved to be efficient in identifying potential reductions in drying time for different sorts of sprue/pine (SP) lumber without compromising the quality of the final product. Simulations also allowed identifying the push rate of 2 feet/h to satisfactorily dry green hem-fir 2-inch lumber.
Initial tests showed that mid-sort sub-alpine (moisture content below approximately 70%) could not be mixed with wet sort SP in a continuous kiln operating at push rate of 4.2 feet/hr because only 73% of the sub-alpine sort dried below 21%. Decreases in push rate will reduce the percentage of sub-alpine fir wets but will also increase the amount of over-dried lumber. Changes in kiln configuration may reduce the drying time but increase the percentage of over-dried lumber.
The results indicated that additional laboratory tests are required to develop drying schedules and temperature profiles in the main drying zone of continuous kilns, drying times and final moisture content distribution.
Interior partition walls for non-residential and high-rise residential construction are an US$8 billion market opportunity in Canada and the United States (Crespell and Poon, 2014). They represent 1.6 billion ft² (150 million m²) of wall area where wood currently has less than 10% market share. To approach this market a new system would be needed to compete against the incumbent system (wood/steel stud plus gypsum). The system would need to have an installed cost before finishing of approximately US$5 per ft² or lower. The system would also need to meet several code requirements for strength, sound transmission and fire resistance (flame spread and burn through). Crespell and Poon further concluded that to be truly transformative, the system would also need to address major trends impacting the building industry including reducing labor, reducing skilled labor, reducing onsite waste, reducing call-backs, and easily recyclable with low environmental impact. A likely market entry point for wood-based interior partition systems may be in taller and larger wood buildings.
Work described in this report investigated the fabrication, installation, acoustic and combustion properties of prototype interior partition wall designs.
Two types of non-structural prototype interior wall panels designated Type A and Type C were installed between two offices in the FPInnovations Vancouver laboratory. Wood sill plates for mounting the prototype panels were fastened to the concrete floor, sides and top of the opening between the two offices to produce a frame for mounting the test panels. Panels were fastened to the frame using dry wall screws. This same method of installation is envisioned in practice. The installation method makes it easy and fast to both install and remove the wall panels.
Acoustic tests showed the difference in ASTC rating measured between a double wall composed of Type A and Type C prototype panels compared with a double wood stud wall with gypsum board faces was approximately 6 ASTC points. A 6 point difference would be clearly noticeable. Although the results of this study are largely qualitative, they suggest that the prototype interior partition panels would have an acoustic advantage compared to stud wall designs.
In a related study summarized in this report, the combustion properties of three prototype interior panel constructions, including Types A and C evaluated in this report, indicated that any of the three types of partition constructions could be used in combustible construction in accordance with Division B of the National Building Code of Canada.
A second related study, also summarized in this report, estimated an installed cost of US$4.07 per ft² including overhead and profit for unfinished panel partitions comparable to panel construction Type C (gypsum/OSB/wood fibre insulation) as evaluated in this study. Thus, there would appear to be potential installed and finished cost advantages for the wood-based panel partitions compared to steel or wood stud walls with gypsum faces.
Other potential advantages of the prototype interior partition panels compared with the most common, currently-used systems (wood/steel stud plus gypsum) include ease and speed of installation, ease and speed of removal, design flexibility, prefabrication including pre-finishing, and easy installation of services.
Based on the positive results of these exploratory studies, further development of wood-based interior partition systems including design, fabrication, installation and in-service performance would appear justified. Knowledge of the products and testing methods developed in these studies would be expected to speed further development.
Fifteen structural composite lumber (SCL) products including laminated-veneer lumber (LVL), laminated strand lumber (LSL), oriented strand lumber (OSL), and parallel strand lumber (PSL) provided by Boise Cascade, LP, West Fraser, and Weyerhaeuser were tested for moisture-related properties in this study, also covering four reference materials: 16-mm Oriented Strand Board (OSB), 19-mm Canadian Softwood Plywood (plywood), 38-mm Douglas-fir and lodgepole pine solid wood. Water absorption, vapour permeance, vapour sorption, and dimensional stability were measured with limited replication by following relevant standards for a purpose of assisting in improving building design and construction, such as hygrothermal modelling of building envelope assemblies, design for vertical differential movement, and on-site moisture management.
To support the implementation of biomass procurement practices, a formal, rigorous, consistent, science-based biomass quality control (QC) program is needed. This program should be designed to determine customer needs, the sources of product variation, and ways of eliminating or minimizing product variation as soon as it occurs. The program should also include a well-designed QC plan and sampling protocol, statistical process control methodologies and tools, formal QC teams, and regular training.
This report describes various statistical QC tools and demonstrates those using examples of biomass moisture content data. These tools can be developed in-house or be purchased, but their integration with existing databases (e.g., LIMS) is recommended. FPInnovations experts can assist in developing customized QC programs for companies and for specific biomass products, and can train QC teams to develop and use the tools presented here.
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This report covers our involvement in phytosanitary-related issues and research in the financial year 2016/17. It addresses actions planned in the 2016/17 project statement of the CFS-funded project entitled: Phytosanitary Measures and deliverables for Codes and Standards work related to phytosanitary issues. It captures our ongoing engagement with CFS, CFIA, and industry, and participation in the key phytosanitary forums including the International Forestry Quarantine Research Group (IFQRG) and the Canadian Forest Phytosanitary Working Group (CFPWG) as these two forums provide guidance to our research in the area.
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A total of 48 peeler blocks and 256 mini-billets were sampled from mills to investigate the effects of yard storage time, and artificial yard drying and sprinkling on residual moisture contents (MCs) and veneer quality. MC in fresh and stored log inventories varied greatly across mills according to geographic location of their wood supply zones, bark damage and loss, and storage time and conditions. The main findings were as follows:
1. DF logs supplied by three BC mills from the Cariboo, Thompson Okanagan, or Kootenay regions were highly variable in wood MC.
2. Winter-cut DF logs with high sapwood MC stored had good bark retention and high moisture retention over 6 and 9 winter-spring months. No effects on veneer peeling roughness from longer-term winter storage up to 9 months.
3. Summer-cut logs had little or no residual bark, or the bark slipped off very easily during debarking. Exposed, bark-free summer-cut logs can dry and crack on edges and ends very quickly, within a few weeks.
4. A marked decline in veneer quality with piling time in Summer for spruce and DF, suggesting an optimum window of processing of such exposed logs of about two weeks. Veneer quality and recovery suffered markedly once the logs had fully air dried mainly because of edge splits creating natural fragmentation of the ribbon.
5. Mills receiving dry-zone logs with much lower MC have a very limited storage window, especially over winter. As little as 2-3 weeks if bark is damaged or missing.
6. Veneer quality could not be definitively tied to log residual MC. Under the controlled laboratory conditions used here it was observed that peeling quality could still be good at low sapwood MC (35-40%) and or very high (MC>100%). Whether this is still the case in mill production is unknown.
7. Logs must never be allowed to fall below FSP and develop edge-checks or deep end checks.
8. Wax emulsion end sealants were effective at hampering drying and end checking on high MC logs, but not effective on low MC logs.
9. Sprinkling retained log freshness and peel quality in high MC DF for several months and prevented log drying and end splitting as well as inner log staining. Ends absorbed considerable extra moisture. Some variability in peel quality was noted.
10. The prototype EM1000 Ground Penetrating Radar could only be reliably used in log edge mode in DF. The unit would also require re-calibration for the very high sapwood MC in spruce and wet-zone DF logs.
There is a need to demonstrate how novel timber-concrete composite floors can span long distances and be a practical alternative to other traditional structural systems. Better understanding of the fire behaviour of these hybrid systems is essential. To achieve this, the fire-resistance of a timber-concrete composite floor assembly, using BC wood products, will be evaluated in accordance with
CAN/ULC-S101 [2]. A 2 hr fire resistance rating will be targeted, as this is the current requirement in high-rise buildings for floor separations between occupancies.
The structural behaviour of this type of system will also be assessed from conducting pull-out tests of the shear connectors.
In conjunction with previous test data, the results of this test will be used to develop an analytical model to assess the structural and fire-resistance of timber-concrete composite floors. 301010618
FPInnovations launched a multi-year research project to measure mid- to high-rise wood buildings’ natural frequencies and damping ratios to expand the database and validate or adapt the existing equations to estimate the natural frequencies. Two high-rise wood buildings equipped with an anemometer and accelerometers are also being constantly monitored to study how the wind excites the building.
Transformative Technologies - Development of "Green" Wood Adhesives for Wood Composite Products
Project no.301006168
E-4956
Location
Québec, Québec
Language
English
Abstract
Chitosan is an amino polysaccharide obtained from the deacetylation of chitin, which is naturally occurring in the shells of a large number of marine crustaceans. Chitosan is soluble in weakly acidic aqueous solutions and possesses adhesive properties. Chitosan has received much attention for medical and industrial applications; however, only limited studies have been conducted on the application of chitosan as a wood adhesive, because its bonding properties on wood are poor. To improve the adhesive quality of chitosan resin, an innovative study on chitosan adhesives has been conducted to use selected fungal species to modify chitosan and improve its bonding properties, to synthesize non-formaldehyde resins with the fungus-modified chitosan, and to enhance urea-formaldehyde (UF) and phenol-formaldehyde (PF) resin performance with the fungus-modified chitosan.
The bonding properties of wood composites made with these chitosan-based green wood adhesives were significantly improved, in terms of lap-shear strength. Unmodified chitosan solution was not compatible with ammonium lignosulfonate, liquid PF resin, soybean resin, powder PF resin, or soybean flour, but was compatible with UF resin, polyvinyl acetate (PVA) resin, and phenol. With the addition of chitosan in UF and PVA resins, both the dry and wet shear strengths of plywood panels were improved, compared with those of panels bonded with the control UF and PVA resins, i.e. without chitosan. A number of chitosan and chitosan-reinforced UF resins were prepared as a binder for particleboard panel manufacturing. Six (6) types of particleboard panels with different levels of resin loadings and press conditions were manufactured. The resulting boards were tested to evaluate the bond quality of the chitosan and chitosan-reinforced UF resins. The test results showed that particleboard panels with good visual quality could be produced with all formulations of chitosan-UF adhesives, even with resin systems made with 1% of chitosan resin only. All chitosan resins used alone or added to UF resins yielded panels with better internal bond (IB) strength than those made with the UF control resin. The panels made with 1% chitosan resin plus 66% UF resin in a 1:1 ratio yielded panels with the highest IB strength and the best overall mechanical properties.
BC Coastal mills will need to diversify the drying technologies currently used and consider new approaches in order to improve productivity, reduce drying costs, regain competiveness and continue to play a significant role in the increasingly stringent quality market for forest products. New demands for drying are related to energy efficiency, low environmental impact and of course, quality of the final product.
The specific objectives of the project were: (1) to improve the conventional drying of 4.5” x 4.5” Douglas-fir lumber, (2) to evaluate the superheated steam/vacuum (SS/V) drying of 4.5” x 4.5” Douglas-fir lumber, (3) to develop a green sorting strategy for hem-fir lumber and (4) to determine the time required to reach 56°C in the core of 5¼ x 5¼ lumber using the requirements of CFIA PI-07 Heat Treatment schedule Option D - Generic Phytosanitary Heat Treatment Schedule, Heat Treatment with Moisture Reduction.
The results showed that the drying time in conventional drying of 4.5” x 4.5” Douglas-fir lumber can be reduced by up to 25% without compromising the quality of the lumber. This can be achieved by increasing the temperature in the final drying stages and using lower relative humidity at the beginning of the drying process. In addition, final moisture content (MC) variation was reduced from 6.2% to 3.9%.
Reductions of drying times from 26% to 41% were observed when drying 4.5” x 4.5” Douglas-fir under SS/V drying. Quality of the lumber at the end of drying was better when compared to the quality of the lumber at the end of conventional drying. In addition, specimens exhibited less final MC variation.
Based on drying rate measurements of green hem-fir lumber dried to 9.0% MC, a new database was developed which in turn was incorporated into OASiS 2.0 software to evaluate different pre-sorting scenarios. Pre-sorting simulations allow end users to estimate the impact of kiln productivity, final MC distribution and drying degrade. The results showed that different correlations between the time to reach 19.0% MC and initial weight or initial MC could be established. The best correlation with an R square of 0.77 was made between initial weight and MC. After performing several simulations with the new database an optimum cut-off point of 65% yielded the best results in terms of potential increase of productivity and quality of the final product.
Wood heating rate test results showed that CFIA Option D may be extended for 5¼ x 5¼ lumber as long as the dry-bulb = 71°C (= 160°F) for 36 hours at the end of the heat treatment. Total heat treatment time required, including the time required to reach 71°C (160°F), is 72 hours.
Glulam and laminated veneer lumber protected by a combination of treatment with borate by two processes, and a film-forming coating, were exposed outdoors in an above-ground field test using a modified post and rail test design. After eight years’ exposure, early to moderate decay was found in untreated test units, while those which were borate-treated by either method were generally sound up to six years and showed greatly reduced decay at eight years.
Glulam manufactured from laminating stock of three species pre-treated with ACQ-D or CA was exposed outdoors in an above-ground field test using a modified post and rail test design. After six years’ exposure, early to moderate decay was found in untreated test units, while those which were preservative-treated were completely sound.
Field tests of untreated and preservative-treated glulam beams in outdoor exposure, in ground contact and above ground, were inspected for decay after five years. Copper azole and ACQ-D-treated material was in excellent condition, while moderate to severe decay was present in untreated non-durable material. Early stages of decay were also noted in yellow cedar glulam in the above-ground test. Using galvanized rather than stainless steel fasteners appeared to have a protective effect against decay in untreated material, supporting the hypothesis that zinc from the sacrificial coating on galvanized bolts inhibits germination of basidiospores.
In British Columbia, due to the decline of lodgepole pine, mills should expect higher volumes of sub-alpine fir in their species mix. The impact on drying is significant. For example, drying times for green SPF (spruce, pine, sub-alpine fir) vary from 24 to 36 hours whereas drying times for sub-alpine fir can easily exceed 70 hours. In addition to longer drying times, the drying of species such as sub-alpine fir using current procedures often results in wet lumber and value loss can be higher than $100 per Mfbm. The potential annual impact for a typical BC mill is estimated to be in the range $1,000,000 to $1,500,000.
Along the years, sawmills have invested millions of dollars in drying technology (conventional drying and green sorting systems) which, for the most part are efficient and relatively low cost. Thus, under the circumstances outlined above, sawmills urgently need to find ways to minimize the problems associated with the drying of sub-alpine fir that is, new procedures or combination of methods, to ensure maximum grade recovery at the end of drying and reduce drying times (increase productivity and lower processing costs). In addition, the pressure exerted by typical longer drying times for sub-alpine fir will impact the drying of spruce and pine. Thus, strategies to speed the drying for those two species are needed to maintain annual production targets.
The main objective of this project is to evaluate several strategies using existing technology so that sawmills can readily implement them throughout their drying operations dealing with larger volumes of sub-alpine fir and for mills with kiln capacity constraints which could compromise their production targets.
This project evaluated a number of opportunities to coastal producers related to kiln drying issues such as drying practices related to high-value products, drying with superheated steam vacuum and internal core temperature monitoring for large timbers during the heat-up phase. In summary, this project included several laboratory studies to evaluate the using superheated steam/vacuum (SS/V) for drying 7/8”x 6, green western red cedar lumber, and 8x8 and 5x(5,6,7,8,9,10,12) Douglas-fir timbers. SS/V drying yielded faster drying schedules when compared to the results obtained in industrial conventional kilns. The results obtained from the SS/V drying of WRC indicated the potential benefits of technology for drying specialty products especially when compared to drying times obtained with conventional drying (longer than 7 days). However, the results obtained also emphasize the importance of green sorting that is, sorting prior to drying to optimize drying times and reduce the variation of final moisture content.
For large cross section Douglas-firs the drying times were between 3 and 14 days depending on the severity of the drying schedule and initial moisture content distribution. The influence of moisture content and cross section during the early and late stages of the heating process were evaluated on 5x5, 6x6 and 8x8 Douglas fir timbers. Thermodynamic equilibrium was reached after 20 hours regardless of moisture content or cross section size. The knowledge is intended to be used to design conventional drying schedules for large cross section timbers.
According to the last forecasts released by BC Hydro, in 20 years the demand for electricity in B.C. will increase about 40%. A typical sawmill in Canada has between 4 and 8 kilns which operate on a constant basis throughout the year. Each kiln dries on average about 16 to 20 kiln charges per month and every kiln charge is on average 250 Mfbm of lumber (based on 2-inch thickness). A typical crossshaft kiln is equipped with fifteen 25 hp motors (approximately 18 kW) so the total installed power per
kiln is about 270 kW. Kilns operate an average of 660 hours per month. Thus, mills with drying operations such as in the example above will consume a significant amount of electricity to dry their
required production.
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Effective preservative treatments for Canadian glulam products are needed to maintain markets for mass timber on building facades, access markets with significant termite hazards, and expand markets for wood bridges. For all three applications, borate-treatment of lamina before gluing would be preferred as it would lead to maximum preservative penetration. However, the need to plane after treatment and prior to gluing removes the best-treated part of the wood, and creates a disposal issue for treated planer shavings. The present research evaluates the block shear resistance of glulam prepared from untreated and borate-treated lamina with a polyurethane adhesive. Borate treatment was associated with a small but statistically significant loss in median shear strength when evaluated dry; however, there was no difference between the performance of untreated and borate-treated samples when exposed to the vacuum-pressure soak/dry or the boil-dry-freeze/dry procedures. Further work is needed to modify the composition or application of the resin to improve shear strength for glulam applications and ensure consistent performance. However, overall, these data indicate that samples prepared from borate-treated lamina perform similarly in terms of block shear resistance to those prepared from untreated lamina.
